Field of the Invention
The present disclosure relates to a process of generating a wide-field-of-view image by combining a plurality of images together.
Description of the Related Art
Methods for obtaining an image having a higher resolution and a wider field of view than an image obtained by a single image capturing operation include a method in which a plurality of images are combined by linking them together to generate a single output image. This process of combining is called image stitching. An example of the image stitching process is as follows. A relative positional relationship between positions of cameras at the time of capturing a plurality of input images is first estimated based on the plurality of input images. Then, the input images are mapped onto a common output image coordinate system on the basis of the estimated relative positional relationship to obtain mappings of the respective input images. In each region where mappings overlap, an alpha blending process (hereinafter, referred to as a blending process) is performed on the overlapping images. In this way, an output image is generated. There are cases where a boundary of images to be linked to each other is determined in the overlapping region and the blending process is performed only in the vicinity of the boundary, instead of performing the blending process in the whole overlapping region.
The relative positions of the input images and the position of the boundary where the blending process is performed are important parameters in the image stitching process described above. Depending on these parameters, artifacts such as multiple images, degradation in sharpness, and discontinuous color changes at the boundary, may occur in the output image. Accordingly, it is desirable that the user be allowed to precisely control these parameters according to their intention particularly in the case where a high-quality output image is desired.
Japanese Patent Laid-Open No. 2001-067488 discloses a technique that allows a user to control parameters of the image stitching process. Specifically, it discloses a configuration that allows the user to move each input image or specify a corresponding point of the input images while viewing the input images on a display screen and to adjust relative positions of the input images.
However, in order to reduce degradation of image sharpness, the blending process is desirably performed only in the vicinity of the boundary that is determined in the overlapping region. In such a case, not only the relative positions of images but also the position of the boundary serve as important parameters to obtain a high-quality output image. With the technique disclosed in Japanese Patent Laid-Open No. 2001-067488, the user is able to control the relative positions of input images but is unable to control the position of the boundary. On the other hand, the boundary is a parameter that can be set two-dimensionally in any way in the overlapping region. A technique for assisting the user in controlling such a parameter having a high degree of freedom is desired.